Rotary compressor including means for reducing vane slot wear

ABSTRACT

A hermetically sealed rotary refrigerant compressor comprising a compression cylinder, a rotor eccentrically rotatable in the cylinder, and a vane slidably mounted in a slot in the cylindrical wall of the cylinder includes means for introducing high pressure refrigerant into the vane slot at wall areas of maximum slot wear and connecting wall areas opposite the areas of maximum wear to low pressure.

United States Patent [1 1 Rinehart 1 May 28, 1974 ROTARY COMPRESSORINCLUDING MEANS FOR REDUCING VANE SLOT WEAR [75] lnven tor: Dean C.Rinehart, Louisville, Ky. [73] Assignee: General Electric Company,

Louisville, Ky.

[22] Filed: July 31, 1972 [21] Appl. N0.: 276,724

[52] U.S. Cl 418/63, 418/243, 418/248 [51] Int. Cl. F01c l/02, F0401/02, F04c 17/02 [58] Field of Search 418/63, 235,243-251 [56]References Cited UNITED STATES PATENTS H 787,224 4/1905 Scofield 418/2483,099,964 8/1963 Eickmann 418/268 3,139,036 6/1964 McGill 413/2483,516,766 6/1970 Monden et al 418/63 Primary Examiner-Carlton R. CroyleAssistant ExaminerJ0hn J Vrablik Attorney, Agent, or Firm-Francis l-l.Boos, Jr.

[ 5 7 ABSTRACT A hermetically sealed rotary refrigerant compressorcomprising a compression cylinder, a rotor eccentrically rotatable inthe cylinder, and a vane slidably mounted in a slot in the cylindricalwall of the cylinder includes means for introducing high pressurerefrigerant into the vane slot at wall areas of maximum slot wear andconnecting wall areas opposite the areas of maximum wear to lowpressure.

3 Claims, SlDrawing Figures A 1 ROTARY COMPRESSOR INCLUDING MEANS FORREDUCING VANE SLOT WEAR BACKGROUND or THE INVENTION A well known type ofhermetically sealed rotary compressor for refrigeration systemscomprises a hermetic casing containing a compressor comprising acylindrical wall member and end plates defining a compression cylinder,a rotor eccentrically mounted within the cylinder and a vane slidablymounted within a vane slot provided in the cylinder wall. The vaneengages the periphery of the rotor to dividethe chamber into a highpressure side and a low pressure side. In the operation of such acompressor, rotation of the rotor draws gas into the low pressure sideand discharges the compressed gas through a discharge port communicatingwith the high pressure side. During the operation of a compressor ofthis type, especially a compressor of large displacement, there is aconsiderable side force exerted on the vane or, more specifically, theportion thereof extending into the compression cylinder, due to the factthat one side or face of the vane is exposed to high or dischargepressure and the other to low or suction pressure. This side force isexerted on the vane slot walls at certain reaction points, these pointsor areas of maximum pressure being at the cylinder edge of the vane slotwall on the suction side of the vane and at the opposite or inner end ofthe vane slot wall on the discharge side of the vane. The result is aconcentration of vane slot wear in these areas.

SUMMARY OF THE INVENTION It is a general object of the present inventionto provide means for employing refrigerant pressures available withinthe compressor to counteract this side force and reduce vane slot wearat the critical wear points.

In accordance with the illustrated embodiment of the present invention,there is provided a-rotary refrigerant compressor contained in ahermetic casing and including end plates and a cylindrical wall definingan annular compression cylinder. A rotor is eccentrically rotatablewithin the cylinder. Spaced suction and discharge ports communicate withthe cylinder and a vane slidably mounted in a slot provided in thecylinder side walls divides the cylinder into low and high pressuresides or chambers. In order to reduce vane slot sidewall wear due tohigh side pressures on the vane, means are provided to produce anopposing gas pressure on the vane in the vane slot wall areas subjectedto maximum vane pressure. Preferably, means are also provided forconnecting vane slot areas on the opposite side of thevane from thepoints of introduction of high pressure refrigerant to suction pressureto assure a pressure differential across the vane opposing the gasforces on the exposed or overhanging end of the vane.

BRIEF DESCRIPTION OF THE DRAWING With reference to the accompanyingdrawing:

FIG. 1 is a side elevational view, partly in section, of a hermeticrefrigeration compressor incorporating the present invention;

FIG. 2 is a partial plan view taken along line 22of FIG. 1;

FIG. 3 is a partial plan view taken along line 3-3 of FIG. 1;

FIG. 4 is a partial sectional view taken along line 4-4 of FIG. 1; and

FIG. 5 is a plan view illustrating a second embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIGS. 1 and 2of the drawing, there is illustrated a hermetic compressor comprising acasing 1 containing a rotary compressor 2 connected by a drive shaft 3to a motor 4.

The compressor includes a wall member or block 5 having an innercylindrical wall 6 which, in combination with an upper end plate 7 and alower end plate 8, define an annular compression cylinder 9. A rotor 11withinthe compression cylinder 9 is eccentrically rotated, in acounterclockwise direction as viewed in FIG. 2, by means of an eccentric'12 formed on the shaft 3. A vane 14 slidably disposed within a radialvane slot 15 in the cylindrical side wall is continuously biased intoengagement with the periphery of the rotor to divide the compressioncylinder into a high pressure side or chamber 16 and a low pressure sideor chamber 17.

The compressor further includes a suction or inlet port 18 on one sideof the vane 14 communicating with the low side 17 and a discharge port19 on the other side of the vane 14 communicating with the high pressureside 16. The high pressure refrigerant discharged through the dischargeport 19 flows through a passage 20 in the upper end plate 7 into theinterior of the case 1 from which it is discharged through a conduit(not shown) to the high pressure side of a refrigeration system. Lowpressure refrigerant is withdrawn from the refrigeration system througha conduit 22 and enters the compression chamber through the suction port18.

During operation of the compressor, as for example, when the rotor is inthe position shown in FIG. 2 of the drawing in which the vane 14 extendsinto the compression chamber 16, one exposed side or face 24 of the vaneis subjected to the high pressure of refrigerant gas being compressed inchamber 16 while the other face of the vane, indicated by the numeral25, is exposed to low or suction pressure. This pressure differential onthe vane exerts a lever, action on the vane biasing the exposed portionof the vane in the direction of rotation of the rotor 11. This resultsin points of maximum vane pressure, these reaction points being adjacentend 28 of the slot side wall 29 on the suction or low pressure side ofthe vane and at the inner end 30 of the vane slot wall 31 on the highpressure side of the vane. Vane slot wear is at its maximum at thesereaction points or areas 28 and 30.

In accordance with the present invention, slot wear in these maximumwear areas or points is substantially reduced by providing opposing orcounteracting gas pressures on the vane within the vane slot. In theillustrated embodiment of the invention the slot wall areas areconnected to a source of high pressure refrigerant gas, and the slotwall areas on the opposite side of the vane from the maximum wear areasare connected to suction pressure. To this end, there are provided alaterally extending groove 34 in the forward or cylinder end of the slotside wall 29 on the suction side of the vane and a similar groove 35 ator adjacent the inner or remote end of the high side vane slot wall 31.In FIGS. 1 and 2 of the drawing, these grooves 34 and 35 are connectedrespectively by means of tubes 38 and 39 extending through the upper endplate 7 to the source of high pressure refrigerant in the upper portionof the case 1. The case pressure gaseous refrigerant thereby introducedinto the grooves 34 and 35 exerts high pressure or pressures on theareas of the vane at these points.

To assure a positive and substantial opposing gas pressure on the vanewithin the slot under all operating conditions, areas of the slot wallson the opposite side of the vane from the areas of maximum wear areconnected to suction or low pressure. The vane slot side wall 29 isprovided with a groove 37 at its inner end opposite groove 35, and theslot side wall 31 includes a groove 38 adjacent its cylinder end and onthe opposite side of the vane from groove 34. These grooves areconnected, for example, by passages 40 in the block to the suction portas illustrated in FIG. 4 of the drawing.

Alternatively, the passage connecting slots 34 and 35 to suctionpressure may be provided in the form of milled grooves in the surface ofend plate 8 overlying the cylinder block. These milled end plate groovesmay have the same configuration as the passages 40 or may cross the vaneslot at suitable points. For example, as shown in FIG. 5, the end platemay include a V- shaped groove including one leg 41 one end 42 of whichcommunicates with port 18 and the other end 43 of which communicateswith the lower end of groove 37. The second leg 44 of the milled groovecrosses the slot 15 between and spaced from grooves 34 and 35 andterminates in an end 45 communicating with the lower end of low pressuregroove 38. The discharge pressure connections to the high pressuregrooves 34 and 35 may be similarly made by means of a groove or groovesin the lower surface of the upper end plate 7 with the inlet end thereofconnected to the discharge chamber 48 (P16. 2) in the block 5.

The operation and advantages of the present invention will bespecifically described by first considering the various gas pressureconditions on the vane in the usual rotary compressor. During most ofthe time any portion extends into the cylinder 9, the pressure inchamber 16 is higher than the suction pressure in chamber 17 so thatthere is a side or lateral gas pressure differential on the extendedportion of the vane in the direction of rotation of rotor 11. In thefully extended position of the vane illustrated in FIG. 2 of thedrawing, the high side pressure is about triple the suction pressure.During the subsequent 180 rotation of the rotor, the surface area of thevane exposed to chamber 16 decreases but the pressure differential inthe cylinder continues to increase until the discharge valve 46 openswhen the high side pressure exceeds case pressure, for example, at aboutfour times suction pressure. When the rotor has rotated to the point atwhich the vane is retracted within the vane slot, the cylinder pressuredifferential is substantially zero. However, since there is some leakageof high pressure refrigerant into the slot on the high pressure side ofthe vane and as the slot area on the opposite or suction side of thevane is at suction pressure, there is still a net pressure differentialacross the cylinder end of the vane causing increased wear particularlyof the cylinder end of suction side slot wall 29.

By the present invention, pressure differentials are provided within theslot for opposing or relieving these wear producing forces on the vane.The high pressure refrigerant introduced into the slot at the points ofmaximum wear, that is, into the grooves 34 and 35, provides gaspressures opposing the cylinder pressures on the vane while theconnections of the slot wall areas opposite these wear areas to suctionpressure assures a positive pressure differential on or across the vaneopposing the wear producing pressures. In addition, at the cylinder endof the slot, the groove 38 relieves any pressure on the vane caused byleakage of high cylinder pressure into the slot.

Since the high pressures in the slot grooves 34, 35 and the lowpressures in grooves 37, 38 remain substantially constant, the pressuredifferentials within the slot across the cylinder end and rear or innerend of the vane also remain substantially constant, and thesedifferentials continuously oppose the cylinder gas forces on the vane tosubstantially decrease slot wear.

While there has been shown and described particular embodiments of thepresent invention it will be understood that it is not limited theretoand it is intended by the appended claims to cover all suchmodifications as fall within the true spirit and scope of the invention.

1 claim:

1. A rotary gas compressor comprising:

means including a cylindrical wall defining an annular compressioncylinder;

a rotor eccentrically rotatable within said cylinder, spaced suction anddischarge ports communicating with said cylinder;

a radially extending slot in said cylindrical wall between said portsand including spaced side walls;

a vane slidably mounted in said slot between said slot side walls andhaving one end engaging said rotor to divide said cylinder into low andhigh pressure chambers within said cylinder whereby the difference ingas pressure on the opposite faces of said vane exerts forces on saidvane concentrating wear at first slot side wall areas adjacent the outercylinder end of one slot side wall on the low pressure side of said vaneand adjacent the inner end of the other slot side wall on the highpressure side of said vane means for reducing slot wear in said firstareas comprising means connecting said first areas to a source of highpressure gas; and

means connecting areas of said slot side walls on opposite sides of saidvane from said first areas to low pressure gas.

2. A hermetic, rotary refrigerant compressor comprising:

a hermetic casing containing high pressure refrigerant gas;

a compressor positioned in said casing and including end plates and acylindrical wall member defining an annular compression cylinder;

a rotor eccentrically rotatable within said cylinder;

spaced suction and discharge ports communicating with said cylinder;

a radially extending slot in said wall member between said ports andincluding spaced side walls;

a vane slidably mounted in said slot between said side walls and biasedinto engagement with said rotor to divide said cylinder into low andhigh pressure chambers whereby the difference in gas pressure on saidvane during operation of said compressor exerts a side force on saidvane concentrating wear 3. The compressor of claim 2 which includes:

laterally extending grooves adjacent the outer and inner ends of both ofsaid slot side walls;

the grooves of the outer end of said one slot side wall and at the innerend of said other side wall receiving the high pressure refrigerant; and

the grooves at the inner end of said one slot side wall and the outerend of said other side wall being connected to the low refrigerantpressure.

1. A rotary gas compressor comprising: means including a cylindricalwall defining an annular compression cylinder; a rotor eccentricallyrotatable within said cylinder, spaced suction and discharge portscommunicating with said cylinder; a radially extending slot in saidcylindrical wall between said ports and including spaced side walls; avane slidably mounted in said slot between said slot side walls andhaving one end engaging said rotor to divide said cylinder into low andhigh pressure chambers within said cylinder whereby the difference ingas pressure on the opposite faces of said vane exerts forces on saidvane concentrating wear at first slot side wall areas adjacent the outercylinder end of one slot side wall on the low pressure side of said vaneand adjacent the inner end of the other slot side wall on the highpressure side of said vane means for reducing slot wear in said firstareas comprising means connecting said first areas to a source of highpressure gas; and means connecting areas of said slot side walls onopposite sides of said vane from said first areas to low pressure gas.2. A hermetic, rotary refrigerant compressor comprising: a hermeticcasing containing high pressure refrigerant gas; a compressor positionedin said casing and including end plates and a cylindrical wall memberdefining an annular compression cylinder; a rotor eccentricallyrotatable within said cylinder; spaced suction and discharge portscommunicating with said cylinder; a radially extending slot in said wallmember between said ports and including spaced side walls; a vaneslidably mounted in said slot between said side walls and biased intoengagement with said rotor to divide said cylinder into low and highpressure chambers whereby the difference in gas pressure on said vaneduring operation of said compressor exerts a side force on said vaneconcentrating wear at first slot side wall areas adjacent the outercylinder end of one slot side wall on the low pressure side of said vaneand adjacent the inner end of the other slot side wall on the highpressure side of said vane; and means for reducing said slot side wallwear comprising means for conducting high pressure refrigerant to saidfirst slot side wall areas, and means connecting an area of each slotside wall on the opposite side of said vane from said first areas to lowrefrigerant pressure.
 3. The compressor of claim 2 which includes:laterally extending grooves adjacent the outer and inner ends of both ofsaid slot side walls; the grooves of the outer end of said one slot sidewall and at the inner end of said other side wall receiving the highpressure refrigerant; and the grooves at the inner end of said one slotside wall and the outer end of said other side wall being connected tothe low refrigerant pressure.